How to enter a large list of DASDs exceeding loader parameter max line length of 896 bytes for RHEL 6 Linux on IBM Z (s390x)

Issue

In certain configurations where the boot loader on IBM Z series needs to be instructed to utilize a very large list of DASDs to accommodate a huge root file system the loader's maximum allowed parameter line length of 896 bytes can be exceeded.

When that happens, validating the zipl.conf file will result in an error message:

# zipl 
Error: The length of the parameters line (### bytes) exceeds the allowed maximum (896 bytes)

On RHEL 7 and newer versions it is possible to specify multiple DASDs either by

• specifying the parameter multiple times,
• or using a comma separated list of bus IDs.,
• or specifying a range of DASDs, by specifying the first and the last bus ID.

However on RHEL 6 the comma separated list of bus IDs, or a range of DASDs by specifying the first and the last bus ID is not available. Each DASD must be specified explicitely on RHEL 6.